Shade For Half Circle Window

I’ve stood in enough sun-drenched living rooms to know the exact look on a homeowner's face when they realize they just threw away several hundred dollars on a custom Shade For Half Circle Window that doesn't actually fit. It usually starts with a DIY measurement taken at the widest point, a quick online order, and a week of anticipation. Then the box arrives. They hold the product up to the glass, and there’s a gaping two-inch light gap at the top or the radius is off by just enough to make the whole thing look like a cheap afterthought. You can’t "trim" a cellular arch. You can’t "stretch" a sunburst shutter. If you get the geometry wrong by even a fraction of an inch, you’re left with a very expensive piece of trash because